Glissomonadida

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Glissomonadida
Orciraptor attacking Actinotaenium.webp
The glissomonad Orciraptor agilis attacking an Actinotaenium cell.
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Clade: Diaphoretickes
Clade: SAR
Phylum: Cercozoa
Class: Sarcomonadea
Subclass: Pediglissa
Order: Glissomonadida
Howe, Bass, Vickerman, Chao & Cavalier-Smith, 2009 [1] emend. Hess & Melkonian, 2013
Suborders & families [2]

Incertae sedis:

The glissomonads are a group of bacterivorous gliding flagellated protists that compose the order Glissomonadida, in the amoeboflagellate phylum Cercozoa. [1] They comprise a vast, largely undescribed diversity of soil and freshwater organisms. [3] They are the sister group to cercomonads; the two orders form a solid clade of gliding soil-dwelling flagellates called Pediglissa. [2]

Contents

Morphology

External appearance

Glissomonads are zooflagellates that aren't strongly amoeboid, and are only covered by a plasma membrane. Their common ancestor is thought to be a biflagellate, with a short anterior flagellum and a long posterior flagellum, that glided on the substrate by moving their posterior flagellum. In gliding descendants, the cell's posterior zone is usually rounded, giving the cell an ovoid shape. Some species may temporarily extend a protoplasmic tail, that unlike most cercomonads doesn't trail along the posterior flagellum. [1] At least two genera, Orciraptor and Viridiraptor , are capable of transforming into a distinctly amoeboid state attached to the surface. [4]

The group also includes descendants that have lost their gliding, mainly Proleptomonas . This genus has another exception to the group: an anterior flagellum that is longer than the posterior, while the posterior is adherent to the cell and not used for gliding. [1]

Internal structure

Most species lack obvious morphological specializations: there is no cytopharynx, deep flagellar groove, or pocket evident. Apart from Proleptomonas , which is exceptionally elongated and has a modified cytoskeleton, the nucleus is usually anterior and attached to the kinetid (= flagellar apparatus) through well-developed fibrous roots. There are typically two posterior and one anterior microtubular centriolar roots. A contractile vacuole is usually seen in the cell's posterior area. The mitochondria have tubular cristae. There is a microbody attached to the posterior side of the nucleus, except in Proleptomonas . The Golgi apparatus is usually seen associated with the nucleus, which doesn't happen in all cercozoans. [1]

Both flagella have the same thickness and are simple, without a paraxonemal rod, hairs or scales, sometimes acronematic (= with an acroneme). Unlike in cercomonads, the ciliary transition zone has a dense transverse plate at the distal end. The anterior flagellum beats like a cilium towards the left, as seen in cercomonads, and is sometimes reduced to a short stub without an axoneme. [1]

Ecology and behavior

Glissomonads are heterotrophic aerobic organisms that almost exclusively inhabit soil or freshwater, where they feed on bacteria. [3] Sexual reproduction is unknown. Cysts are present in the group, and have smooth walls. [1]

Phylogeny

The cladogram below depicts the evolutionary relationships between most of the glissomonad families: [5]

Glissomonadida

Cercomonadida

Classification

The current classification is: [2]

Related Research Articles

<span class="mw-page-title-main">Cercozoa</span> Group of single-celled organisms

Cercozoa is a phylum of diverse single-celled eukaryotes. They lack shared morphological characteristics at the microscopic level, and are instead united by molecular phylogenies of rRNA and actin or polyubiquitin. They were the first major eukaryotic group to be recognized mainly through molecular phylogenies. They are the natural predators of many species of bacteria. They are closely related to the phylum Retaria, comprising amoeboids that usually have complex shells, and together form a supergroup called Rhizaria.

<span class="mw-page-title-main">Cercomonad</span> Order of single-celled organisms

Cercomonads are small amoeboflagellates, widespread in aqueous habitats and common in soils.

<span class="mw-page-title-main">Monadofilosa</span> Group of protists

Monadofilosa is a grouping of Cercozoa. These organisms are single-celled amoeboid protists.

<span class="mw-page-title-main">Thecofilosea</span> Class of single-celled organisms

Thecofilosea is a class of unicellular testate amoebae belonging to the phylum Cercozoa. They are amoeboflagellates, organisms with flagella and pseudopodia, distinguished from other cercozoa by their scale-lacking test composed of organic material. They are closely related to the Imbricatea, a group of testate amoebae with tests composed of inorganic silica scales.

<span class="mw-page-title-main">Sarcomonadea</span> Class of flagellate protists

The sarcomonads or class Sarcomonadea are a group of amoeboid biciliate protists in the phylum Cercozoa. They are characterized by a propensity to move through gliding on their posterior cilium or through filopodia, a lack of scales or external theca, a soft cell surface without obvious cortical filamentous or membranous skeleton, two cilia without scales or hairs, tubular mitochondrial cristae, near-spherical extrusomes, and a microbody attached to the nucleus.

Proleptomonas is a genus of coprophilic protists, containing the single species Proleptomonas faecicola. It belongs to the phylum Cercozoa, although it was previously considered the only free-living kinetoplastid. It is the only member of family Proleptomonadidae.

<i>Katabia</i> Genus of heterotrophic protists

Katabia is a genus of soil-dwelling heterotrophic flagellate cercozoans containing the single species Katabia gromovi, and the only member of family Katabiidae.

Platysulcus tardus is an eukaryotic microorganism that was recently discovered to be the earliest diverging lineage of the Heterokont phylogenetic tree. It is the only member of the family Platysulcidae, order Platysulcida and class Platysulcea.

Neocercomonas is a protist genus of the order Cercomonadida. It consists of single-celled bacteriophagous organisms that usually live on or nearby terrestrial plants, both above and belowground. Species are biflagellate and may grow up to 60 micrometers long, with a trailing tail-like mass of protoplasm at their posterior end and a pair of roots connecting their posterior flagellum to the cytoskeleton.

The paracercomonads are a group of cercozoan protists. Taxonomically, they comprise the family Paracercomonadidae, order Paracercomonadida and subclass Paracercomonada. Due to their morphological similarities to the cercomonads, members of this family were grouped with Cercomonas and similar taxa from the beginning. However, their similarities are due to convergent evolution.

<span class="mw-page-title-main">Ventrifilosa</span> Superclass of protists

Ventrifilosa is a highly diverse group of phagotrophic protists that glide through their flagella and emit filose pseudopods from their ventral side for feeding. Because of their mixture of amoeba and flagellate characteristics, they are amoeboflagellates. Members of this group are the Imbricatea, Sarcomonadea and Thecofilosea.

Cryptofilida is an order of small heterotrophic protists in the phylum Cercozoa. They are filose amoebae that lack cilia and gliding, and are instead characterized by movement through branching or unbranched granular filopodia that are appressed to the substrate during their feeding.

Massisteriidae is a family of granofilosean protists within the phylum Cercozoa.

Pediglissa is a subclass of phagotrophic protists that inhabit soil or freshwater habitats. They were defined in 2018 according to phylogenetic analyses that showed a clade containing the orders Cercomonadida and Glissomonadida. They're the sister group of Paracercomonadida.

<span class="mw-page-title-main">Viridiraptoridae</span> Family of predatorial protists

Viridiraptoridae, previously known as clade X, is a clade of heterotrophic protists in the phylum Cercozoa. They're a family of glissomonads, a group containing a vast, mostly undescribed diversity of soil and freshwater organisms.

<i>Orciraptor</i> Genus of predatorial protists

Orciraptor is a genus of heterotrophic protists, containing the single species Orciraptor agilis. It belongs to the family Viridiraptoridae, in the phylum Cercozoa.

Viridiraptor is a genus of heterotrophic protists, containing the single species Viridiraptor invadens. It belongs to the family Viridiraptoridae, in the phylum Cercozoa.

The pansomonads, suborder Pansomonadina, are a group of heterotrophic protists that belong to the phylum Cercozoa. Some of them are helioflagellates, with characteristics of heliozoans and amoebo-flagellates.

Saccharomycomorpha is a genus of non-flagellated protists with a rare yeast-like appearance, containing the single species Saccharomycomorpha psychra. It is the only genus of the family Saccharomycomorphidae, within the cercozoan order Glissomonadida. Before its description in 2021 it was known as clade T, recovered from environmental DNA in previous phylogenetic analyses.

<span class="mw-page-title-main">Amoeboflagellate</span> Cellular body type

An amoeboflagellate is any eukaryotic organism capable of behaving as an amoeba and as a flagellate at some point during their life cycle. Amoeboflagellates present both pseudopodia and at least one flagellum, often simultaneously.

References

  1. 1 2 3 4 5 6 7 Howe AT, Bass D, Vickerman K, Chao EE, Cavalier-Smith T (2009). "Phylogeny, Taxonomy, and Astounding Genetic Diversity of Glissomonadida ord. nov., The Dominant Gliding Zooflagellates in Soil (Protozoa: Cercozoa)". Protist. 160 (2): 159–189. doi:10.1016/j.protis.2008.11.007. ISSN   1434-4610.
  2. 1 2 3 Cavalier-Smith, Thomas; Chao, Ema E.; Lewis, Rhodri (April 2018). "Multigene phylogeny and cell evolution of chromist infrakingdom Rhizaria: contrasting cell organisation of sister phyla Cercozoa and Retaria". Protoplasma. 255 (5): 1517–1574. doi:10.1007/s00709-018-1241-1. PMC   6133090 . PMID   29666938.
  3. 1 2 Howe AT, Bass D, Chao EE, Cavalier-Smith T (2011). "New Genera, Species, and Improved Phylogeny of Glissomonadida (Cercozoa)". Protist. 162 (5): 710–722. doi:10.1016/j.protis.2011.06.002. ISSN   1434-4610.
  4. Hess S, Melkonian M (2013). "The Mystery of Clade X: Orciraptor gen. nov. and Viridiraptor gen. nov. are Highly Specialised, Algivorous Amoeboflagellates (Glissomonadida, Cercozoa)". Protist. 164 (5): 706–747. doi:10.1016/j.protis.2013.07.003. ISSN   1434-4610.
  5. 1 2 Feng, Jian-Ju; He, Chen-Yang; Jiang, Shu-Hua; Zhang, Tao; Yu, Li-Yan (2021). "Saccharomycomorpha psychra n. g., n. sp., a Novel Member of Glissmonadida (Cercozoa) Isolated from Arctic and Antarctica". Journal of Eukaryotic Microbiology. 68 (3). doi:10.1111/jeu.12840.